How to Solve Count Unique Characters of All Substrings of a Given String Problem
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Count Unique Characters of All Substrings of a Given String
Let's define a function countUniqueChars(s) that returns the number of unique characters in s. For example, calling countUniqueChars(s) if s = "LEETCODE" then "L", "T", "C", "O", "D" are the unique ch...
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Understanding the Count Unique Characters of All Substrings of a Given String Problem
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Problem Statement
Let's define a function countUniqueChars(s) that returns the number of unique characters in s. For example, calling countUniqueChars(s) if s = "LEETCODE" then "L", "T", "C", "O", "D" are the unique characters since they appear only once in s, therefore countUniqueChars(s) = 5. Given a string s, return the sum of countUniqueChars(t) where t is a substring of s. The test cases are generated such that the answer fits in a 32-bit integer. Notice that some substrings can be repeated so in this case you have to count the repeated ones too.
Count Unique Characters of All Substrings of a Given String
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Examples
s = "ABC"10All possible substrings are: "A","B","C","AB","BC" and "ABC". Every substring is composed with only unique letters. Sum of lengths of all substring is 1 + 1 + 1 + 2 + 2 + 3 = 10
s = "ABA"8The same as example 1, except countUniqueChars("ABA") = 1.
s = "LEETCODE"92Constraints
1 <= s.length <= 105s consists of uppercase English letters only.How Interview Coder Helps with Leetcode Problems
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